/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.util.function;

import org.apache.flink.util.ExceptionUtils;

import java.util.function.BiFunction;

/**
 * {@link BiFunction} interface which can throw exceptions.
 *
 * @param <T> type of the first parameter
 * @param <U> type of the second parameter
 * @param <R> type of the return type
 * @param <E> type of the exception which can be thrown
 */
@FunctionalInterface
public interface BiFunctionWithException<T, U, R, E extends Throwable> {

	/**
	 * Apply the given values t and u to obtain the resulting value. The operation can
	 * throw an exception.
	 *
	 * @param t first parameter
	 * @param u second parameter
	 * @return result value
	 * @throws E if the operation fails
	 */
	R apply(T t, U u) throws E;

	/**
	 * Convert at {@link BiFunctionWithException} into a {@link BiFunction}.
	 *
	 * @param biFunctionWithException function with exception to convert into a function
	 * @param <A> input type
	 * @param <B> output type
	 * @return {@link BiFunction} which throws all checked exception as an unchecked exception.
	 */
	static <A, B, C> BiFunction<A, B, C> unchecked(BiFunctionWithException<A, B, C, ?> biFunctionWithException) {
		return (A a, B b) -> {
			try {
				return biFunctionWithException.apply(a, b);
			} catch (Throwable t) {
				ExceptionUtils.rethrow(t);
				// we need this to appease the compiler :-(
				return null;
			}
		};
	}
}
